Description (Adapted from Application): This research proposal deals with the development of two highly parallelizable, fully three-dimensional reconstruction models with extensive applicability in the field of electron microscopy (EM) of crystals, based on the geometry of the 3D Torus. One of the imaging models proposed is aimed at the study of the atomic structure of crystals formed by atoms of more than one kind, by means of transmission EM. The present work is an enhancement to the previous successful model developed specifically for tomography of crystals endowed with a single kind of atom. The other tomography model allows the imaging of crystallized biological molecules and molecular aggregates and complexes, such as RNA, DNA, proteins and ribosomes, which can be crystallized. This work is fundamental in that it could permit the extraction of previously unobtainable structural and morphological information from the electron microscopy of biomolecules. Due to a robust signal-to-noise ratio, this reconstruction technique offers an additional advantage by requiring lower radiation doses than conventional methods, which could guarantee sample integrity by limiting the structural degradation in complex organic species. A comparative study of the quality and speed of the reconstruction will be performed on data obtained from crystallized specimens of current interest, taking into consideration the performance of other existing imaging models. As a byproduct of the proposed research, the investigators expect to produce software packages to be used in EM facilities, for both models. The long-term objective of this proposal is to create an image processing unit at the University of Puerto Rico, integrated to a multidisciplinary environment, aimed at assisting the needs of our researchers in the biomedical area.